Tuning scale



H. M; LEWIS TUNING sum.

Jan. 18, 1933.

Original Filed Sept. 25, 1931 2 Sheets$heet 1 INVENTOR HA R010 MIME/F lEW/J ATTORNEYS ms A L51 1.. 6 M m5 Jan. 18, 1938.

H. M. LEWIS TUNING SCALE Original Filed Sept 25 1931 2 Sheets-Sheet 2 v INVENTOR HA R010 MILLER LEM IS BY I M 4-41 ATTORN Reissued Jan. 1a, 1938 UNITED STATES to Hazeltine' TUNING scam Harold Miller Lewis, GreatNeuk,

Corporati No Y s Original No. 1,987,857, dated January 15, 1935,

Serial No. 565,027, September :5; 1831. cation for reissue October 103,727 '14 Claims.

The present invention relates to a tuning system, or, more particularly, to such. a system as adapted for usein a short wave receiver or converter.

A short wave converter is an apparatus which, when used in conjunction with any broadcast re-- ceiver, permits thereception of short wave sig-' nals by the said broadcast receiver. The converter comprises an oscillator and modulator, by which the short wave signal currents are converted into-currents of a frequency within the tuning range of the broadcast receiver.. The current of this frequency, which frequency will be referred to hereinafter as the intermediate frequency", is amplified, detected and reproduced by the broadcast receiver.

The frequency range covered by the short wave band is approximately from 1500 kc. (200 meters) to 20,000 'kc. meters). This range of frequencies is so great that it is not practical to tune a circuit through the entire range by the variation of a single tuning element. Some arrangement must be provided for changing both of the frequency determining elements; that is, both the inductance and the capacity. In accordance with the usual practice, the tuning is actually done by varying the capacity of a variable condenser, and the'inductance is changed in steps to permit the condenser to tune the circuit throughout the various portions of the range;

In practicing the present invention, the shortwave band is divided into three bands which will be referred to in this application as the "short wave band", the "middle wave band, and the long 'wave band.

The inductance used in tuning the radio frequency circuits of the short wave receiver, or the I radio frequency circuit and oscillator circuits of a converter, are usually wound on removable forms commonly known as "plug-in coils, which coils are changed when desiring to go from due of the short wave bands to another. A system of this type has the disadvantages that it is expensive to manufacture and requires shifting of coils when operating.

' -,Various systems have been proposed by which the inductance of the tuning coils is changed. in

stepsby means of switches. However, the leads and switch mechanisms introduce capacities whichconsiderably lessen the range of the tuning condensers, and usually the resulting large num- Arr z. isss .'iserm no.

(crass- 4o) I typ orin which switches are used to change the indu'ctances, the tuning condenser has a single scale which'is arbitrarily marked. This requires noting the coil" inuse-or' switch position, as well I as the condenser setting, when logglng" a sta- 5 tion, as it is necessary to know both the scale indication and the inductance in order to tune the circuits to a given i'requency. s

It is the object ofthe present invention to overcome the above noted difllculty and to provide an indicating device for a short wave re-. ceiving apparatus in which the frequency to which the tuning device is tuned may be re "corded, regardless or the band in which the set is being operated, and, urther,tc provide means 15 by which the rrequency band in which the set is being operated is indicated at all times.

Furthermore, the usual scale used in connection with the short wave. receiver or converter permits operation of the apparatus with con! slderably more case in the long wave band, due

to the fact that the movement of the tuning control required to separate the different stations at the long wave end of the band is considerably greater than that required 'to separate the stations at the short wave end of the band. It is, therefore, the further object of this invention to provide a scale inwhich the stations are separated by approidmately the same amount at both ends of the tuning range- These and rurther objects of my invention will become apparent from the following specifications taken in connection with the appended claims and with theaccompanying drawings.

In accomplishing the ob'jectsof the present invention the inductances of the frequency determining circuit or the oscillator and the input circuit are provided with switches for short-circuiting the long wave and middle wave portions of the winding, when operating the oscillator to 40 receive signals in the middle wave band and short Y wave band, respectively.

In order to permit continuous rotation of the tuning dial in either direction to progressively .tune the converter through the entire band, the condensers used in both the modulator input and oscillator circuits are each provided with double stators and double rotors so constructed that when the capacity between one of the pair of rotors and stators is maximum, that between the other pair of rotors and stators is This feature is covered more particularly in appllca tion otwilliam A. MacDonald for Condensers," Serial No. 564,997, illed concurrently herewith.

The tuning control knob is geared to the conswitching arrangement constitute no part of the present invention, but are described fully in 00-- denser by 4:1 reduction gear. In. turn the con denser is geared to the dial by a 2:1 step-up'gear so that 180 rotation of the condenser corresponds to a full rotation of. the dial. The dial rotates in the direction in which the tuning knob. is turned. As the dial moves from left to right the frequencies received become higher. This dial has thereon three indicating scales, the outer scale being for indicating the frequencies in the short wave band, and the inner scale being for indicating the frequencies in the long wave band. The scales pass by indicator lights placed behind the dial within a compartment which permits illumination of but a single scale by each indicator light, and a switch operated simultaneously with ,the wave changing switches operates to light the appropriate scale. The long wave scale indications appear at the bottom window and the top window permits observation oi the short wave scale indications. This arrangement allows a greater spread for the short wave channels of which there are considerably more than the long wave channels. 5

- In order to permit the operation of a single control knob to control the frequency of reception,

regardless o1 which oi-the three bands the converter is operating in, there is provided a gang switch mechanismoperated by means of the condenser control knob at the appropriate instant as the dial is rotated from one to another of the irequency bands. The specific details of the pending application of Harold Miller Lewis tor Switching arrangementf, Serial No. 565,026, filed concurrently herewith.

' It can thus be seen that an arrangement has been provided by which the set can be tuned" through the entire-short wave band by the operation of a single control, and by which the frequency for which this apparatus is set to respond is automatically indicated at all times as the set is tuned.

Attention is now invited to the accompanying drawings in which:

Fig. 1 is a circuit diagram of a converter embodying the present invention; ahd

Figs. 2 and 3 are front and side elevations, re-

spectively, oi the indicator dial and control arrangement oi the converter comprising a part of the present invention. Fig. 3a is an inverted control mechanism. J v

Referring now to Fig. l, the antenna circuit includes the antenna III, the ground II, the trap circuit l2, comprising the inductance l3 and condenser ll, the primary winding l5, and a portion oi. the secondary IS. The inductance l3 and the condenser-ll oi the trap circuit I! are so proportioned that said circuit is resonant to the intermediate frequency produced by the short wave converter. The input circuit or the con-' 'verter is connected to the grid 01 modulator deplan view 0! the switch vice ll, which may be any thermionic tube,

though that shownis of the screen grid type. The input circuit iatuned by means of the condenser ill, which may be adouble condenser employing as shown, a single rotor and two stators so arranged that the capacity obtained between the rotor and one stator is maximum, when the capacity between the rotor and the other stator is minimum. The connections to the stators are controiledby means of the switch 23. The actual condenser includes two stators and two rotors, so arranged that when one rotor is entirely within mentioned above.

oases stator; This is fully described in the application The function of the condenser and switch arrangement will be explained later.

The tapped secondary It is connected by means of switch 24, so that any of the tapped portions of the secondary may be included in the input circuit. The switch is so connected-that the unused portions of thewinding are short-circuited.

For producing the heterodyne frequency for combining with'the incoming signal and thus producing the intermediate frequency, there is provided the oscillator 25. This oscillator tube is of the single grid type and includes in its grid circuit the secondary Ill of the oscillation transformer, the primary or which is connected in the plate circuit which includes stopping condenser 43. similar to i6 01' the antenna transformer, and the connections to said secondary are controlled by means oi switch 34. The-grid return of the oscillation circuit is completed through the biasing resistor 27, which is connected to the cathode,

of the tube 25. The frequency of the oscillation circuit is determined by means of condenser 3|, which is similar to condenser 2|, and is connected to be operated therewith in a uni-control manner by means of the control knob 22 associated with the indicator dial 26. i

The connections to the two portions of the condenser ii are controlled by rneans of switch 33.

Padding condensers HM arid S are provided across the two portions of condenser, as shown, ior the purpose of aligning the oscillation circuit with the input of modulator H in the middle wave range and short wave range, respectively. Padding condenser ilh is connected across the long wave portion of the inductance winding 40, so that when the switch SI is on contact L this condenser is practically in shunt with the condensers 3i and US for iusting the alignment in contact M, the condenser llL is in shunt with condensers SI-and 31', and the total series capacity is at that time the sum of these three condensers.

In series with condenser 3i are provided series condensers 38, 31 and 38, the connections to which are controlled by means of the switch 33. Each oi these condensers is provided with the padding condenser 36', 31', or 38', respectively, for the purpose of correcting the alignment at oscillator circuit with the modulator input in the various irequency bands. In the middle frequency band, as has just been stated, the condenser, L is in shunt with 31 and 31'. Coupling coils M and 45 coupled to the middle and long wave portions oi the secondary M, respectively, are included in the cathode circuit of the modulator II. This circuit also includes the biasing resistor M shunted by by-pass condenser l! for the purpose of causing tube 'l'l to act as a modulator.-

The plate and screen grid potential are provided by means of the power supply source 20 As shown, the dial 28 includes three scaleafla, 28b, and its, these scales covering the short wave band, middle wave band, and long-wave band, respectively.

The secondary 40 is a tapped winding the long wave range. When the switch 3| is on It is to be noted that in order to get better spacing of the frequency indicators, the short dial 25, as the condenser motion to get the frequency separation required to separate the various stations is less in the short wave band than it is in the long wave band.

In furtherance of this general idea, the tuning condensers may be chosen to give a straight-line frequency characteristic, which gives an equal frequency spaced scale, and if it is desired the circumference of the various scales, and hence their radii, may be properly chosen so that all of the scales shall have the same uniform frequency spacing.

With this arrangement, adjustment of the tuningcondenser 2| between the limits of its capacitance ran'ge causes'the circuit l5, 2| to be tuned over a band of frequencies having a ratio between the limiting frequencies of the band which is the same irrespective of which portion of the second: ary winding i5 is utilized, but increasing in mean frequency and in actual band width as the active portion of the winding I5 is decreased. Hence, if 4 scales of the same length are utilized for all of the frequency bands to which the system is tunable, the spacings between indicia representing like frequency separations on the scales and, thus, the adjustments of the tuning condenser ,2l become successively less in the order of increasing mean frequencies of the bands and inverse- 1y proportional to the mean frequencies of the bands, or:

where 81, S2, and S: are the spacings between indicia representing a given frequency separation having successively lower mean frequencies F1, F2, and F3.

By making the portion of the scales, corresponding to a given displacement of the tuning bandsof successively greater lengths, as, for example, by increasing the radius of the scales in the manner illustrated, the relation ,given above is modified to the extent that:

From this last relation it is apparent that like frequency separations on the individual scales are in a ratio, from scale to scale, in the order of decreasing frequency, which is greater than the inverse ratio of the mean frequencies of the corresponding frequency bands. It is pointed out that the term spacing is used herein to denote the average distance between adjacent indicia of the scale, in order to make the relations herein capacitance law of the tuning element used, that is, whether it is of the straight-hue frequency may be made to have the same length spacings on the several scales. For example, assume that.

70 the length of each scale corresponds to the same total displacement of the tuningelement and as-.

some also bands of 1600-8200 'kilocycles, 3200- 8400 kilocycles, and 6400-12300 kilocycles haying band widths of 1600 kllocycles, 3200 -kllocy les,

7 and 6400 kilocy'cles, respectively,

wave scale-is placed inthe outer position on the" on the respective scales corresponding to bands element, for the successively higher frequency statedperfectly general and independent of the and mean frequencies of 2400 kilocycles, 4800 kilocycles, and

a 2 to 1 ratio is required between the diameters or radii of the successive scales if the scale spacing is to be equal on all three scales. Then the radius of the middle wave scale will be twice that of the long wave scale, and the radius of the short wave scale will be twice that of the middle wave scaleor four times that of'the long wave scale. I

-9600 kilocycles, respectively. With these bands For the purpose of indicating in whichof the frequency ranges the converter is operating, each of the scales is provided with one of the illuminating lights 11a, 1lb, or 1| 0, controlled by means of switch 39 to light them when tuning through the short wave band, middle wave band, and long wave band, respectively.

Switches 23, 24, 3-3, 34, 35 and 39 are so arranged as to be simultaneously operated and also to be actuated by the control knob 22 as the con- I densers are tuned through the limiting capacities for one of the frequency bands. Thus, the rotation of the control knob 22 results in'the actua tion of the switches 23 and 33, resulting in switching of the connections to condensers'2l and 3|, respectively, to give the opposite capacity extreme for the modulator and oscillator circuits. Switch 39 is simultaneously operated changing the lighting of the indicating lights andthus indicating the change in the frequency band by changing the indication from one to another of the scales. Although specific means .for actuating the switches constitute no part of the presentinvention, and are described fully in application, Serial No. 565,026, referred to above, they willb'e described briefly hereinafter.

Included in the plate supply to the modulator I1 is, the inductance 50. This inductance may have a high inherent capacity as indicated by capacity 5|, or an actual condenser may be placed in shunt therewith. The inductance and 'capac-' ity, however, are so proportioned that frequencies other than the desired intermediate frequency will be by-passed.

A connection from the output of modulator I1 is made through condenser 52 and lead 53 to the antenna binding post of they receiver 51. This connection is made through a shielded cable 54,

which may, for example, be a BX cable, from the walls of which the lead 53 is spaced by means of bakelite spacers 55. Also connected through the cable 54 is the ground connection 55, which is connected to the-ground binding post of receiver 51. The capacity 52 and the inherent capacity between the leads and 55 are so proportioned that they constitute a dummy-antenna to properly load the modulator l1, and to prevent misalignment of the input of receiver 51; Switch 50 is provided between the antenna Ill and the lead 53 by means of which the antenna may .be directly connected to the input of the receiver .51 when it is desired to receive signals in the broadcast band directly on receiver 51.

The receiver 51 may be of any well known type, and is provided with the usual sound reproducing device 58. 'I-he'speciflc details of neither 51 nor 58 constitute any part of the present invention.

The receiver is tuned to the intermediate frequency which it is desired to utilize, preferably 1,000 kc. The direct reception of signals of 1,000

fier of signals of 1,000 kc. frequency by means of would be excluded by the inductance 50. It is thus seen that a number of provisionshave been made to prevent the interference of broadcast signals with the short wave signals being received by means of the converter.

Attention is now invited to Figs.v2, 3 and 3a which show front and side elevations, and inverted plan view respectively, of theindicator dial and condenser and switch control mechanism. The chassls of the converter is represented at I00, and has the condenser 2I mounted thereon in a central position, a portion only of which is shown in Fig. 2. The shaft 03 of the condenser has a. gear I02 and a switch throwbar I04 secured on the end thereof, the function of which will be described more fully hereinafter.

The control knob 22 is mountedon shaft IIS and is journaled in the front of the chassis I00. A gear 8, secured to said shaft, meshes with the gear I02. The gears I02 and IIB are so proportioned that a 1:4 ratio is provided. For permitting this engagement the chassis I00 is provided with an opening or cutaway portion us, which alsopermits the switch throw-bar III to pass therethrough and engage the switch shifting' gear I22.

Also mounted on the chassis I00 are the vertical supporting member I08 and the front panel member I06. Mounted in the vertical member I00 isthe journal I09, in which is journaled the shaft I I0 towhichis secured the indicator dial 28. Secured also to the shaft III! is the gear II2 which meshes with the gear I02 on .the condenser tuning throughout various portions of said band,

shaft 83.

Mounted upon the vertical member I08 is the hood member I ll providing three small compartments in which are mounted the indicator lights Ila, llb and No. It can be seen that the dial 26 passes over the front of the compartments and the light passing therethrough is framed by the viewing window openings I20a, I2Ilb, and

I200, respectively, cut in the panel member I06.

A vertical wire I2l is arranged over the openings'in the front of chambers III to provide an index mark which is visible only through that portion of the dial which is illuminated by one of the lights H.

The switch I20 is provided for controlling the power supply-to the converter.

The gear 2 has half as many teeth as the gear I02, andthe gear 0 has one-fourth as many. Thus it can be seen that the scale "will rotate once for every half revolution .of the con- -denser shaft 03, and for everyrtwo revolutions of the tuning. control knob; j

The switch-throw bar IIII' passes through an opening H9 in the chassis I00 and engages the teeth N2 of the switch-shifting gear I22 which latter is pivoted beneath the chassis. The pin 1 Ill on the gear I22 is connected by any appropriate linkage to control the motion of the switch arms of the gang switch. Each timethe condenser direction or the other. The switch 20 which is inrotor has made one ,half revolution. one end of the t hrow-bar engages a tooth I42 of the gear I22 .and'rotates it through a small angle. Thus the switch throw-bar I04 actuates a gang switch so that each time the condenser rotor has made one-half revolution, the switch, full details of which are shown in the copending application referredto above, will be actuated to change the connections to shiftthe frequency band in one cluded in the gang switch operates to light the cases tune, it is obvious that the features relatingto said condenser in the higher frequency portions of those for the long wave lengths, and the length 'nating the scale relative to which saidindicating covering a ,broadwave length band in which an .-through various portions of the band, means industinent of said condenser in the higher freappropiiate indicator light, and thus the scale in which the apparatus is set to operate is indicated at all times. I

Whereas, the above description of the features of the present invention refers particularly to a converter for converting the incoming short wave signal to a current of a frequency within the broadcast band to which an ordinary receiver can a tuning system and indicating system as required 1 in the short wave band are equally applicable to a short wave receiver of the ordinary type.

'What is claimed is: v

1. In a receiver adapted to receive signals covering in a broad wave length band in which an inductance is varied in steps to permit tuning through various portions of the band, means including a variable condenser for tuning said receiver over each of various portions of said band, said means effecting progressively increasing 2 frequency adjustments for a given adjustment of of said band, an indicator dial operative with said variable condenser, a plurality of scales on said dial, said scales being spaced from the center of said dial by such a distance that they each have substantially the same frequency indication separation, an indicating means for indicating the position of said variable condenser, and means for changing the scale relative to which said'indicating means is eflective as the inductance of a circuit of the receiver is altered in steps.

2. In a radio receiver adapted to receive signals covering abroad wave length band, which includes an inductance variable in steps to permit the combination of means including a variable tuning element for tuning said'receiver over each of said various portions of said band, said means effecting progressively increasing frequency adjustments for a given adjustment of said element in the higher frequency portions of said band, a dial associated with said element and movable therewith, a plurality of frequency calibrated scales on said dial, the radii of the scales for the short wave lengths being greater than the radii of the portions of the scales for the short wave lengths corresponding to a given displacement of said tuning element being substantially greater than those of the scales for the long wave lengths, means for indicating the frequency to which said receiver is tuned to respond, and means for desigmeans is effective as said inductance is varied in steps.

3. In a receiver adapted to receive signals inductance is varied in steps to permit tuning eluding avariable condenser for tuning said receiver, said means effecting progressively increasing frequency adjustments for "a given adquency portions of said band, a plurality of scales operatively related toisaid condenser 'for indicating the frequency to which said receiver is tuned, the portions of the scales corresponding to a given displacement of said variable condenser for the successive short wave portions of the band being of progressively greater length than those for the. long wave portion of said band, an indicating means for indicating the position of'said variable condenser, and means for designating the scale relative to which said indicating means 5 is eflective as the inductance of a circuit of the r ceiver is altered in steps. v

4. In a radio receiver for receiving radio sig nals covering a broad frequency band and employing reactance elements variable in steps to permit tuning throughout the various portions of the band, the combination with means including a variable reactance elementfcr timing throughout the various portions of the band, said means effecting progressively increasing frequency ad-. Justments for a given adjustment of said variable reactance element in the higher frequency portions of said band, of a plurality of scale means, each of different length and each bearing indices of the' frequencies covered by said varia-' ble reactance element while operating to tune within the respective portions of said band, a frequency-indicating means for cooperation with said scales, means for moving said scales and said indicator means relative to each other as said variable reactance element is varied to tune said receiver, and means for causing the scales having the longer portions corresponding to a given displacement of said variable reactance element and the indicating means to cooperate to indicatefrequencies in the high-frequency portions of said band and the scales having the shorter portions corresponding to said given displacement and the indicating means to cooperate to indicate-frequencies in the low-frequency portions of said band.

' 5. In a radio receiver for tuning in a plurality of frequency bands means including a tuning element continuously variable for tuning said receiver over each of various portions of said band,

said means effecting progressively increasing fre-' quency adjustments of said condenser in the higher frequency portions of said band, and a tuning element variable in steps, scales associated with said continuously variable element for indicating frequency in each of said bands, the portion of each scale, corresponding to a given displacement of said tuning element, being longer as the frequency band to which it relates is higher, a control means for varying said continuously variable element and for moving said scales relative to an index and means for indicating the scale in use.

6. In a radio receiver for tuning over a plurality of frequency bands, a tunable circuit including a first tuning element continuously var: iable. over each of said bands, said means effecting progressively increasing a frequency adjustments for a given adjustment of said first tuning element in the bands having progressively higher mean frequency, and a second tuningelement adjustable in steps corresponding to said bands,

scales for indicatingv in each of said bands the frequency to wh ch said variable tuning element is adjusted, the portion of each scale, corresponding to a given. displacement of said first tuning element, being longer as the frequency band to which it relates is higher, means associated with said second tuning element for selec ing the scale corresponding .to the band for reception in which said second tuning element is adjusted, and means controlling simultaneous-f ly the variation of said variableituning element and the indication on said selected'scale of the frequency to which said receiver is tuned.

7. In a multi-brind radio receiver adapted to receve signals in a broad frequency range including a plurality of frequency bands, reactance means adjustable in steps for-selectively tuning said receiver to any of said bands, means including a variable reactance element for tuning throughout-each of 'said bands, said means effecting progressively increasing frequency adjustments for-a given adjustment of said variable reactance element in the higher frequency bands, a plurality of scales individually corresponding to said frequency bands and having different lengths with the scale having the longest portion corresponding to a given displacement of said variable reactance element bearing indicia of the frequencies included in the highest frequency band and the scales having the successively shorter portions corresponding to said given displacement bearing indicia of the frequencies in- I dividually included in the successively lower frequency bands, whereby like. frequency separations of the individual scales are in a ratio, from scale to scale in the order of decreasing band frequency, which is greater than the inverse ratio of the mean frequencies of the corresponding bands, and indicating means cooperating with said scales.

8. In a multi-band radio receiver adapted to receive signals in a broad frequency range including aplurality of frequency bands, reactance means adjustable in steps for selectively tuning said receiver to any of said bands, means including a variable reactance element for tuning throughout each of said bands, said means effecting progressively increasing frequency adjustments for a givenadjustment of said variable reactance element in the higher frequency bands, a plurality of scales individually corresponding to said frequency bands and having different lengths with the scale having the longest portion corresponding to a given displacement of said variable reactance element bearing indicia of the frequencies.

included in 'the highest frequency band and the scales having the successively shorter portions corresponding to said given displacement bearing indicia of the frequencies individually included in the successively lower frequency bands, whereby like frequency separations on the individual scales are in a ratio, from scale to scalein the order of decreasing band frequency, which is greaterthanthe inverse ratio of y the mean frequencies of the corresponding bands, and an index cooperating with said scales,'said index and scales, being relatively movable in response to adjustment of said variable reactance element.

9. In a multi-band radio receiver adapted to receive signals in a broad frequency range including a plurality of frequency bands, reactance means adjustable in steps for selectively tuning said frequency bands and having different lengths with the scale having the longest portion corresponding to agiven displacement of said variable reactance element bearing indicia of the frequencies included in the highest frequency band and the scales having the successively shorter portions corresponding to said given displacement bearing 'indicia of the frequencies individually included in the successively lower frequency bands, whereby like frequencyseparations on the individual scales are in a ratio, from scale to scale in the order of decreasing band' frequency, which is greater than the inverse ratio of the mean frequencies of the corresponding bands, an index cooperating with said scales for indicating, on

I I scale, corresponding to a given displacement of the scale corresponding to the band to which said receiver istuned, the frequency to which said I receiver is tuned,'and means responsive to adjustment of said adjustable reactance means for indicating the scale corresponding to the band to a which the receiver is tuned.

10. In a multi-bandradio receiver adapted to receive signals in a broad frequency range ineluding a'high-frequency band and a low-fre-- quency band, reactance means adjustable selectively to tune said receiver to either of said bands, means including a variable reactance element for tuning throughout each of said bands, said means effecting greater frequency adjustments for a given adjustment of said variable reactance element in the band of higher frequencies, a first scalebearing indicia of the frequencies included in said low-frequency band, a second scale bearing indicia of the frequencies included in said high-frequency band, the portion of said second said variable reactance element, being longer than said first scale, whereby given frequency separations on that of said second scale are in a ratio to like frequency separations on said first scale which is greater than the inverse ratio of the mean frequenciesof the corresponding bands, and indicating means, cooperating with said scales.

11. In a'multi-band radio receiver adapted to first scale bearing indicia of the frequencies included in said low-frequency band, a second scale bearing indicia of the frequencies included in said high-frequency band, said'second scale having a portion corresponding to a given displacement of said variable reactance element which is longer thanthat of said first scale. whereby given frequency separations on said second scale are in a ratio to like frequency separations on said first scale which is greaterathan the inverse ratio of the mean frequencies of the corresponding bands.

an index cooperating with said scales, said index and scales being relatively movable in response to adjustments of said variable reactance'element, and means responsive to adjustment of said adjustable reactance means for indicating the scale corresponding to the band to which said receiver is tuned.

12. In a multi-band radio receiver adapted to receive signals in a broad frequency range includinga high-frequency band and a low-frequency band. reactance meansadjustable selectively to tune said receiver to either of said bands..

means including a variable reactance element for timing throughout each of said bands, said means effecting greater frequency adjustment for a given adjustmentofsaid variable reactance element in the band of higher frequencies, a dial having thereon a pair of continuously visible one of'said scales bearing indicia of the frequencies included in said low-frequency band,

the other of said scales bearing indicia of the frequencies included in said high-frequency band and having the portion corresponding to a given adjustment of said variable reactance element substhntially longer than that of said one of said scales, whereby given frequency separations on said other of said scales are in a ratio to like frequency separations on said one of said scales which is greater than the inverse ratio of the mean frequencies of the corresponding bands, an index, said index and scales being relatively movable in response to adjustment of said variable reactan'ce element to indicate on'thascale, corresponding to the band to which said receiver is tuned, the frequency to' which said receiver is tuned, and means for selectively illuminating the scales to indicate the scale corresponding to the band to which said receiver is tuned.

13. In a multi-band radio receiver adapted to receive'signals in a broad frequency range including a plurality of frequency bands, reactance means adjustable in steps for selectively tuning said receiver to any of said bands, means including a variable reactance element for tuning throughout each of said bands, said means effecting progressively increasing frequency adjust,- ments for a, given adjustment of said variable:

reactance element in the bands of higher fre 1 quencies, a plurality of scales individually corre sponding to said frequency bands, said scales having portions corresponding to a given adjustment of said variable reactance element increasingly longer in the bands of higher frequencies, the relation between said scales and the reactances of said tuning means being such that like frequency separations on the individual scales are in a ratio, from scale to scale in the order of decreasing band frequency, which is greater than the inverse ratio of the mean frequencies of the corresponding bands, and indicating means cooperating with said scales.

14. In a multi-band radio receiver adapted to receive signals in a. broad frequency range inv eluding a high-frequency band and a low-frequency band, reactance means adjustable selectively to tune said receiver to either of said bands,

means including a variable reactance element for tuning throughout each of said-bands, said means effecting greater frequency adjustment for a given adjustment of said variable reactance element in the band of higher frequencies, a first scale hearing indicia of frequencies insaid low-frequency band, a second scale bearing indicia of the frequencies included in said liigh frequency band, the portions of said second scale corresponding to a given adjustment of said variable reactance element being substantially longer than that of said first scale; the relation between said scales and the reactances of said tuning meansbeing such that given frequency separations on said second scale are in a ratio to like frequency separations on said first scale which is greater than I the ratio of the mean frequency of the low-fre+ quency band to the mean frequency of the highfrequency band, and indicating means cooperating with said scales. a

, HAROLn MILLER Lewis, 

